There’s a new parlor game in Washington these days: Trying to figure out how the U.S. and China can work together to tackle climate change.

The Senate Foreign Relations Committee hosted the latest round today, as resident China optimist John Kerry called in a slate of heavyweights to explain just how important it is to get China on board and just how difficult that is going to be.

The testimony—from the Carnegie Institute’s Bill Chandler, the Council on Foreign Relations’ Elizabeth Economy, and Brookings’ Kenneth Lieberthal—was chock full of praise for all the green things China is doing these days. There’s lots of it—from big plans for wind farms to dynamiting dinky and dirty old coal-fired power plants.

But what really stands out is how much China’s environmental and economic challenges dwarf everything else in the world. Put another way, Beijing is aware of the need to do something about climate change. Beijing is also acutely aware that it has 800 million people still living in primitive conditions whose only way out is quick economic development.

There is still plenty of hand-wringing about China’s addiction to coal and what that means for global greenhouse-gas emissions. Ms. Economy summed it up nicely:

In 2006, China added 90 gigawatts of coal fired power capacity—enough to emit over 500 million tons of CO2 per year for 40 years; by comparison, the European Union’s entire Kyoto reduction commitment is 300 million tons of CO2.

But China’s got more to worry about than new power plants: As part of its push for development, it hopes to “urbanize” about 400 million Chinese over the next two decades. Think of all the headaches America has saving a single Detroit, and then think about building a new one from scratch every month. As Mr. Lieberthal put it:

[T]he current pace of migration of about 15 million people per year moving into cities is likely to continue for another 15-20 years. The resulting requirements for new power generation, building construction, transportation, education, health services, etc., means that, effectively, China has to build urban infrastructure and create urban jobs for a new, relatively poor city of 1.25 million people every month, and that will likely continue for the better part of the next two decades. The key industries that support the related infrastructure development – cement, steel, petrochemicals, power, and aluminum – have been among the fastest-growing industries in China over the past half decade and are also the most important sources of greenhouse gas emissions.

Compared to that, the litany of proposals the experts suggested for U.S.-Chinese cooperation on climate change—sharing technology on clean coal, and working together to build better car batteries, for instance—seems a bit tame.

Tackling climate change without China might well be impossible. But given the country’s plans for economic development, getting China on board won’t be a silver bullet, either.